This invention relates to a channel-type papermakers' felt primarily intended for use in the press or dewatering sections of a papermakers' machine. It may be used in the press roll section, which may have plain or grooved rolls, and also is intended for use in connection with suction rolls or suction boxes or the like. The felt can be used as a cylinder top or bottom felt and as a yankee pickup felt.
In U.S. Pat. No. 3,613,258 issued to Jamieson on Oct. 19, 1971, there is disclosed a papermakers' felt whichas attached to the bottom surface thereof, longitudinally extending monofilament plastic strands. The strands are extruded and applied hot to the back surface of a needled felt in the warp direction to form a corresponding series of intermediate channels. The longitudinally extending extruded filaments are inherently formed of a different material than that of the synthetic and animal fibers making up the felt itself, and difficulty has been encountered in effectively bonding the filaments to the base of the felt so that the filaments did not peel off or otherwise become unattached from the felt in use. A further difficulty is in the selection of plastic which has the requisite resiliency to pass repeatedly through the press rolls without extensive flattening or loss of shape and resultant loss of the channels therebetween.
A multiple material or duplex woven base having a batting needled to the upper surface thereof is disclosed in British Patent No. 1,030,994 published May 25, 1966. In the British patent, the base material consists of a two-ply woven yarn in which a lower ply of two-ply base fabric is formed with larger diameter synthetic yarns with a high degree of twist woven in a plain weave of open construction, and interwoven with an upper ply of two-ply base fabric of relatively fine diameter yarns woven in a close weave construction. A non-woven batting is needled into the upper surface thereof. No channel structure is achieved by the British construction. Rather, a regular pattern of drainage holes are formed by the open weave of the lower ply which entrap the water.